Checking If a Function Pointer is Valid

Question: I am collecting a number of function pointers in C++ and before I call them I want to check to see if they have been set. I really want to avoid calling them if they aren't valid. I have tried
the following "if func != Null { ... " but I get an error.

Answer: First of all, there's no 'Null' in C++. The constant NULL is all uppercase. However, it's not a keyword so you have to #include a header file to make its definition visible to the compiler. The best way check for nullness is to compare the pointer (any type of pointer, including a pointer to member) to the literal zero: